The community structure of arbuscular mycorrhizal fungi in roots of maize grown in a 50-year monoculture

We assessed the diversity of arbuscular mycorrhizal (AM) fungi colonizing maize roots grown in a long-term monoculture experiment established at Martonvásár, Hungary, 50 years ago to understand the effect of this extremely long monoculture on the community structure of these organisms. Mycorrhizal colonization of root samples was analyzed by PCR amplification and sequencing of partial ribosomal small subunit DNA fragments of fungal origin. Of the 257 sequences recovered, 203 belonged to Glomeromycota AM fungi. Phylogenetic analysis assigned the Glomeromycota sequences into 22 operational taxonomic units belonging to three families including Archaeosporaceae, Glomeraceae, and Paraglomeraceae. In agreement with previous reports, Glomus group A fungi dominated the arbuscular mycorrhizal fungi community of maize, but we found a relatively high richness of phylotypes within this group even after such an extreme and durable reduction of host plant diversity. Agricultural practices, including mineral fertilization and incorporating stalk residues, significantly affected the diversity within Glomus group A.